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pc: sanity check bda value in lowraminit() to avoid overflow with efi

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This commit is contained in:
cinap_lenrek 2014-10-12 20:18:59 +02:00
parent ca694c51ef
commit cc6ab31891
1 changed files with 6 additions and 4 deletions
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10
sys/src/9/pc/memory.c
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@ -376,7 +376,7 @@ sigsearch(char* signature)
static void
lowraminit(void)
{
ulong n, pa, x;
ulong pa, x;
uchar *bda;
/*
@ -387,9 +387,11 @@ lowraminit(void)
*/
x = PADDR(CPU0END);
bda = (uchar*)KADDR(0x400);
n = ((bda[0x14]<<8)|bda[0x13])*KB-x;
mapfree(&rmapram, x, n);
memset(KADDR(x), 0, n); /* keep us honest */
pa = ((bda[0x14]<<8)|bda[0x13])*KB;
if(x < pa){
mapfree(&rmapram, x, pa-x);
memset(KADDR(x), 0, pa-x); /* keep us honest */
}
x = PADDR(PGROUND((ulong)end));
pa = MemMin;